1. Field of the Invention
The present invention relates generally to the field of power disconnect switches. More particularly, the invention relates to an electrical power disconnect switch in which the trip operation of the switch is capable of being performed both manually and electrically.
2. Related Art
Disconnect switches are commonly found on a variety of electrically operated industrial equipment. Such switches are also employed in automobiles. The primary function of disconnect switches is to remove a machine or piece of equipment, or more generically speaking, a "load", from a power source. Representative disconnect switches and relays include those of U.S. Pat. No. 2,591,335, issued to Bordelon, U.S. Pat. No. 2,286,375 issued to Ray, and U.S. Pat. No. 4,095,213, issued to Hayden.
It is often desirable that the disconnect switch open automatically to remove the load from the power source. Automatic disconnection may be advisable when an alarm condition is present, such as when a malfunction in the load or other equipment occurs, or when the equipment is turned off. For example, in the disconnect switch for an automobile described in the Hayden patent referenced above, a coil becomes energized when the automobile ignition is turned on, and electro-magnetic forces are created which hold the electrical contacts together. When the ignition switch is turned off, the coil is deenergized and the contacts open.
Additionally, it is often desirable that the disconnect switch be manually operable, in order to provide a "panic button" feature. Manual disconnection of the load is also done when routine maintenance on the equipment is performed. The present invention provides new and advantageous techniques for providing a disconnect switch having both electrical (or automatic) and manual tripping characteristics.